27 Mar
2025
27 Mar
'25
8:02 p.m.
[CC updated]
Hi folks,
This thread started on the groff@gnu list, so I'm looping it back in.
https://lists.gnu.org/archive/html/groff/2025-02/msg00088.html
https://lists.gnu.org/archive/html/groff/2025-03/msg00070.html
The formatter, GNU troff:
* catenates its input into a single stream, disregarding any file
"boundaries" except the first and the last;
* does not generally require the input to end with a newline;
* throws a warning diagnostic if the input ends with the *roff escape
character (and ignores that character);
* warns about and discards NUL characters from the input (along with
several others that are invalid as input);
* always terminates its _output_ files (whether in Kernighan's "trout"
format [originally seen in CSTR #97], or "approximate" [`troff -a`]
format) with newlines (ASCII LF);
* and writes only printable ASCII characters and the space in
"trout"/"grout" or approximate outputs, with one esoteric
exception.[1]
I'd like to know what, specifically, this program should be doing
differently.
Regards,
Branden
[1] The `cf` request permits the copying of abritrary bytes from the
input file named by it to "grout" output. In the forthcoming
_groff_ 1.24.0, the formatter handles this request only in the
non-default "unsafe mode" enabled by the `-U` command-line option.
Quoting groff's Texinfo manual:
-- Request: .trf ["]file
-- Request: .cf ["]file
Copy FILE as "throughput" to GNU 'troff' output. Each line of
FILE
is output as if preceded by '\!', but is not interpreted by the
formatter. If FILE does not end with a newline, 'trf' appends one.
Both requests break the line before reading FILE, unless invoked
with the no-break control character.
When used in a diversion, these requests embed a node (*note Gtroff
Internals::) in it that, when interpolated, causes the contents of
FILE to be copied to the output. In AT&T 'troff', 'cf' does
so
even if a diversion is in use; this behavior is so anomalous that
it must be considered a bug.
'cf' copies the contents of FILE completely unprocessed; it is
therefore an error to use this request in safer mode, which is the
default. Invoke GNU 'troff' or a front end with the '-U' option
to
enable unsafe mode.
'trf' discards invalid input characters; recall *note
Identifiers::.
For 'cf', within a diversion, "completely unprocessed" means
that
each line of a file to be inserted is handled as if it were
preceded by '\!\\!'.
*Caution:* Use of these requests can put syntactically invalid
content into the formatter's output, which 'groff''s output
drivers
then fail to process. One application is to pass instructions to a
postprocessor that interprets FILE's contents and filters it out
before sending it to the output device.